I've flown with CX on quite a few occasions and they are very decent. On any airline, they tend not to allow jump seats if they are training (although I have flown on a B Midland 733 where a new captain was being checked out and got the j/s). Cathay is generally very decent. My best flight was from KIX to HKG on a 330 and they couldn't have done more - jump seat for t/o and landing and although they don't allow photos, if you get the j/s, I figure you've done fairly well!!
On Delta or any US airline, "please do not ask to visit the cockpit during the flight or take the jump seat as a smack in the kisser often offends"!! (Seriously, it's against regulations and the FAA tends to get a tiny bit cross about it.)